net: Use netlink_ns_capable to verify the permisions of netlink messages

It is possible by passing a netlink socket to a more privileged
executable and then to fool that executable into writing to the socket
data that happens to be valid netlink message to do something that
privileged executable did not intend to do.

To keep this from happening replace bare capable and ns_capable calls
with netlink_capable, netlink_net_calls and netlink_ns_capable calls.
Which act the same as the previous calls except they verify that the
opener of the socket had the desired permissions as well.

Reported-by: Andy Lutomirski <[e-mail]>
Signed-off-by: "Eric W. Biederman" <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

crypto/crypto_user.c

···
 	type -= CRYPTO_MSG_BASE;
 	link = &crypto_dispatch[type];
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if ((type == (CRYPTO_MSG_GETALG - CRYPTO_MSG_BASE) &&

drivers/connector/cn_proc.c

···
 		return;
 
 	/* Can only change if privileged. */
-	if (!capable(CAP_NET_ADMIN)) {
+	if (!__netlink_ns_capable(nsp, &init_user_ns, CAP_NET_ADMIN)) {
 		err = EPERM;
 		goto out;
 	}

drivers/scsi/scsi_netlink.c

···
 			goto next_msg;
 		}
 
-		if (!capable(CAP_SYS_ADMIN)) {
+		if (!netlink_capable(skb, CAP_SYS_ADMIN)) {
 			err = -EPERM;
 			goto next_msg;
 		}

kernel/audit.c

···
 		if ((task_active_pid_ns(current) != &init_pid_ns))
 			return -EPERM;
 
-		if (!capable(CAP_AUDIT_CONTROL))
+		if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
 			err = -EPERM;
 		break;
 	case AUDIT_USER:
 	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
 	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
-		if (!capable(CAP_AUDIT_WRITE))
+		if (!netlink_capable(skb, CAP_AUDIT_WRITE))
 			err = -EPERM;
 		break;
 	default:  /* bad msg */

net/can/gw.c

···
 	u8 limhops = 0;
 	int err = 0;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if (nlmsg_len(nlh) < sizeof(*r))
···
 	u8 limhops = 0;
 	int err = 0;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if (nlmsg_len(nlh) < sizeof(*r))

net/core/rtnetlink.c

···
 	return 0;
 }
 
-static int do_setlink(struct net_device *dev, struct ifinfomsg *ifm,
+static int do_setlink(const struct sk_buff *skb,
+		      struct net_device *dev, struct ifinfomsg *ifm,
 		      struct nlattr **tb, char *ifname, int modified)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
···
 			err = PTR_ERR(net);
 			goto errout;
 		}
-		if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) {
+		if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)) {
 			err = -EPERM;
 			goto errout;
 		}
···
 	if (err < 0)
 		goto errout;
 
-	err = do_setlink(dev, ifm, tb, ifname, 0);
+	err = do_setlink(skb, dev, ifm, tb, ifname, 0);
 errout:
 	return err;
 }
···
 }
 EXPORT_SYMBOL(rtnl_create_link);
 
-static int rtnl_group_changelink(struct net *net, int group,
+static int rtnl_group_changelink(const struct sk_buff *skb,
+		struct net *net, int group,
 		struct ifinfomsg *ifm,
 		struct nlattr **tb)
 {
···
 
 	for_each_netdev(net, dev) {
 		if (dev->group == group) {
-			err = do_setlink(dev, ifm, tb, NULL, 0);
+			err = do_setlink(skb, dev, ifm, tb, NULL, 0);
 			if (err < 0)
 				return err;
 		}
···
 				modified = 1;
 			}
 
-			return do_setlink(dev, ifm, tb, ifname, modified);
+			return do_setlink(skb, dev, ifm, tb, ifname, modified);
 		}
 
 		if (!(nlh->nlmsg_flags & NLM_F_CREATE)) {
 			if (ifm->ifi_index == 0 && tb[IFLA_GROUP])
-				return rtnl_group_changelink(net,
+				return rtnl_group_changelink(skb, net,
 						nla_get_u32(tb[IFLA_GROUP]),
 						ifm, tb);
 			return -ENODEV;
···
 	int err = -EINVAL;
 	__u8 *addr;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	err = nlmsg_parse(nlh, sizeof(*ndm), tb, NDA_MAX, NULL);
···
 	sz_idx = type>>2;
 	kind = type&3;
 
-	if (kind != 2 && !ns_capable(net->user_ns, CAP_NET_ADMIN))
+	if (kind != 2 && !netlink_net_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if (kind == 2 && nlh->nlmsg_flags&NLM_F_DUMP) {

net/dcb/dcbnl.c

···
 	struct nlmsghdr *reply_nlh = NULL;
 	const struct reply_func *fn;
 
-	if ((nlh->nlmsg_type == RTM_SETDCB) && !capable(CAP_NET_ADMIN))
+	if ((nlh->nlmsg_type == RTM_SETDCB) && !netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	ret = nlmsg_parse(nlh, sizeof(*dcb), tb, DCB_ATTR_MAX,

net/decnet/dn_dev.c

···
 	struct dn_ifaddr __rcu **ifap;
 	int err = -EINVAL;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if (!net_eq(net, &init_net))
···
 	struct dn_ifaddr *ifa;
 	int err;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if (!net_eq(net, &init_net))

net/decnet/dn_fib.c

···
 	struct nlattr *attrs[RTA_MAX+1];
 	int err;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if (!net_eq(net, &init_net))
···
 	struct nlattr *attrs[RTA_MAX+1];
 	int err;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if (!net_eq(net, &init_net))

net/decnet/netfilter/dn_rtmsg.c

···
 	if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
 		return;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		RCV_SKB_FAIL(-EPERM);
 
 	/* Eventually we might send routing messages too */

net/netfilter/nfnetlink.c

···
 	    skb->len < nlh->nlmsg_len)
 		return;
 
-	if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) {
+	if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
 		netlink_ack(skb, nlh, -EPERM);
 		return;
 	}

net/netlink/genetlink.c

···
 		return -EOPNOTSUPP;
 
 	if ((ops->flags & GENL_ADMIN_PERM) &&
-	    !capable(CAP_NET_ADMIN))
+	    !netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {

net/packet/diag.c

···
 
 	net = sock_net(skb->sk);
 	req = nlmsg_data(cb->nlh);
-	may_report_filterinfo = ns_capable(net->user_ns, CAP_NET_ADMIN);
+	may_report_filterinfo = netlink_net_capable(cb->skb, CAP_NET_ADMIN);
 
 	mutex_lock(&net->packet.sklist_lock);
 	sk_for_each(sk, &net->packet.sklist) {

net/phonet/pn_netlink.c

···
 	int err;
 	u8 pnaddr;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (!netlink_capable(skb, CAP_SYS_ADMIN))
 		return -EPERM;
 
 	ASSERT_RTNL();
···
 	int err;
 	u8 dst;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (!netlink_capable(skb, CAP_SYS_ADMIN))
 		return -EPERM;
 
 	ASSERT_RTNL();

net/sched/act_api.c

···
 	u32 portid = skb ? NETLINK_CB(skb).portid : 0;
 	int ret = 0, ovr = 0;
 
-	if ((n->nlmsg_type != RTM_GETACTION) && !capable(CAP_NET_ADMIN))
+	if ((n->nlmsg_type != RTM_GETACTION) && !netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	ret = nlmsg_parse(n, sizeof(struct tcamsg), tca, TCA_ACT_MAX, NULL);

net/sched/cls_api.c

···
 	int err;
 	int tp_created = 0;
 
-	if ((n->nlmsg_type != RTM_GETTFILTER) && !capable(CAP_NET_ADMIN))
+	if ((n->nlmsg_type != RTM_GETTFILTER) && !netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 replay:

net/sched/sch_api.c

···
 	struct Qdisc *p = NULL;
 	int err;
 
-	if ((n->nlmsg_type != RTM_GETQDISC) && !capable(CAP_NET_ADMIN))
+	if ((n->nlmsg_type != RTM_GETQDISC) && !netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	err = nlmsg_parse(n, sizeof(*tcm), tca, TCA_MAX, NULL);
···
 	struct Qdisc *q, *p;
 	int err;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 replay:
···
 	u32 qid;
 	int err;
 
-	if ((n->nlmsg_type != RTM_GETTCLASS) && !capable(CAP_NET_ADMIN))
+	if ((n->nlmsg_type != RTM_GETTCLASS) && !netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	err = nlmsg_parse(n, sizeof(*tcm), tca, TCA_MAX, NULL);

net/tipc/netlink.c

···
 	int hdr_space = nlmsg_total_size(GENL_HDRLEN + TIPC_GENL_HDRLEN);
 	u16 cmd;
 
-	if ((req_userhdr->cmd & 0xC000) && (!capable(CAP_NET_ADMIN)))
+	if ((req_userhdr->cmd & 0xC000) && (!netlink_capable(skb, CAP_NET_ADMIN)))
 		cmd = TIPC_CMD_NOT_NET_ADMIN;
 	else
 		cmd = req_userhdr->cmd;

net/xfrm/xfrm_user.c

···
 	link = &xfrm_dispatch[type];
 
 	/* All operations require privileges, even GET */
-	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+	if (!netlink_net_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if ((type == (XFRM_MSG_GETSA - XFRM_MSG_BASE) ||